Superconducting Sr0.875Nd0.125CuO2−δ thin films

Abstract

Single-phase Sr0.875Nd0.125CuO2−δ (SNCO) thin films of the ‘‘infinite-layer’’ structure were fabricated by a pulsed-laser deposition technique. The films directly grown on SrTiO3 (100) substrates had superconductivity onset temperatures around 20 K, but zero resistances were not observed down to 4.2 K. The a-axis length of the film samples did not exceed the values reported for bulk SNCO samples. It was demonstrated that, when deposited onto a Pr2CuO4 buffer layer formed on a SrTiO3 substrate, the a-axis length of the thin film SNCO increased up to 0.395 nm which was comparable to that for bulk SNCO. The film sample exhibited a zero resistance state below 7 K. Thermoelectric-power measurements indicated that the carrier density for the film deposited on a Pr2CuO4 buffer layer was higher than that for the film fabricated without a buffer layer.